JPS61269853A - Positive plate of clad type lead-acid battery - Google Patents

Abstract

PURPOSE:To remarkably increase discharge performance by preparing slurry-like paste by mixing graphite having large anisotropy to lead powder and kneading the mixture with dilute sulfuric acid, or kneading the mixture with water, then mixing to dilute sulfuric acid, and filling the paste in a tube. CONSTITUTION:Graphite having large anisotropy is mixed to lead powder. The mixture is kneaded with a specified amount of water, and dilute sulfuric acid is gradually added to the mixture with it kneaded. When the amount of kneading solution per 1kg of lead powder is Xml/kg, and PbSO4 content in the slurry in the absolute dry state is Y%, the slurry-like paste is prepared so that the values of X and Y meet the following relations; 0.015X<=Y<=0.05X, Y<=-0.04X+46, 300<=X<=800, and 5<=Y<=24. The slurry-like paste is filled in a clad tube.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a positive electrode plate for a clad lead-acid battery (hereinafter referred to as a clad positive electrode plate).

Conventional technology and its problems The clad type positive electrode plate is a porous tube made of glass fiber, acid-resistant, oxidation-resistant synthetic fiber, etc., with a lead alloy core placed in the center of the lattice, filled with lead powder, and soaked. It is manufactured through processes such as , chemical conversion, etc. Since the porous tube prevents the active material from falling off, a positive electrode plate with a longer life than a paste-type positive electrode plate can be obtained.

The fine lead powder is filled into the tube while being vibrated. When the degree of vibration is insufficient, hollow parts are created in the tube that are not filled with lead powder, so naturally the density will be higher when the tube is filled with lead powder to every corner. Therefore, the density of the active material also increases, making it difficult to improve the utilization rate of the positive electrode active material. Furthermore, even if it were possible to fill the tube with lead powder at a low packing density without creating cavities, the bond between the lead powder particles would not be sufficient.
Chemical formation is difficult to proceed, and the utilization rate of the positive electrode active material is also low. Lead dust, which is a harmful substance, is generated when filling the cassette with lead powder, which is not good for the working environment. Therefore, instead of filling with lead powder, a method of filling with a slurry paste prepared by kneading lead powder with water or dilute sulfuric acid has been considered. However, if the paste is too hard, it will be difficult to fill it, and if the paste is forcibly filled, problems such as damage to the tube will occur. To make a slurry-like paste that is easy to fill, mix water or dilute sulfuric acid with lead powder.
It is necessary to increase the amount (hereinafter referred to as the amount of mixing solution) considerably. However, such a slurry-like paste inevitably has a low density and the above-mentioned problem occurs again. That is, the bond between the active material particles is weak and chemical formation is difficult to proceed, resulting in a low utilization rate of the positive electrode active material.

Means for Solving the Problems The present invention eliminates the above problems and provides a clad type positive electrode plate with excellent performance. This method utilizes the property of expanding and producing a graphite intercalation compound with excellent conductivity. That is, a slurry paste prepared by adding highly anisotropic graphite to lead powder and mixing well, then kneading the mixture with dilute sulfuric acid, or kneading the mixture with water and then mixing with dilute sulfuric acid. It is filled with The clad type positive electrode plate produced in this way undergoes sufficient oxidation because the highly anisotropic graphite added to the active material undergoes anodic oxidation and expands to change the structure of the active material during battery charging. Coupled with the good conductivity of the produced graphite intercalation compound, a clad positive electrode plate with excellent discharge performance can be obtained.

Example Examples of the present invention will be described below.

PbO (approximately 15%, balance) lead powder with a particle size of 100 to 1
1% of large anisotropic graphite of 200 μm was added and mixed well. First, 1 ha of this mixture is kneaded with a certain amount of water,
Then, while kneading the paste, dilute sulfuric acid having a specific gravity of 1.40 was gradually added. Figure 1 shows the amount of solution (total of water and dilute sulfuric acid)
PbSO in the paste in an absolutely dry state when changing the
The relationship between the 4 content and the properties of the paste is shown below. The figure shows that a slurry-like paste that can be smoothly filled into the tube is obtained within the area surrounded by the curved line.

Outside this region, the paste may be liquid and leak through the tube, or it may be too hard and difficult to fill. When the amount of solution is 300 to 600,117 kQ, a suitable slurry paste can be obtained with a relatively wide range of Pb SOa content, and as the amount of solution is increased, the optimum Pb SOa content can be obtained.
The content rate is limited.

Next, paste pastes A to I in the area surrounded by the curve in the figure with a tube diameter of 9! lIlφ Clad type lattice rest (height 10cm
+
After initial charging, 5-hour rate discharge and 30-minute rate discharge were performed at an electrolytic solution specific gravity of 1.26, and the results of comparison between the presence and absence of anisotropic graphite addition are shown in the table. Since the active material layer differs depending on the amount of mixing solution, the test results are expressed as the utilization rate of the positive electrode active material (ratio of actual capacity to theoretical capacity).

As is clear from the test results, at any discharge rate, the positive electrode active material utilization rate of the battery in which anisotropic graphite was added to the positive electrode paste exceeded that in the battery without the addition, reaching more than twice as much at the maximum. However, the battery type (■), in which a mixture of lead powder and anisotropic graphite is kneaded with only water, has a lower positive electrode active material utilization rate than the others, and it is necessary to form Pb SO4 in the positive electrode paste. I understand.

In this example, a slurry paste was prepared by kneading a mixture of lead powder and anisotropic graphite with water, then adding dilute sulfuric acid with a specific gravity of 1.40 and kneading. Dilute sulfuric acid may also be added. However, in this case, PbSO4 is generated in the paste at the same time as dilute sulfuric acid is added, so sufficient kneading is required. In addition, in the case where anisotropic graphite was not added, many cracks were observed in the active material inside the tube, but when anisotropic graphite was added, no cracks were observed at all because the graphite expanded during battery charging. There wasn't. In this example, only the case where 1 wt % of highly anisotropic graphite was added was shown, but similar effects were obtained when the amount added was 0.3 wt % or more. The particle size used in this example is good. When preparing a slurry-like paste, the mixing surface and the Pb SO 4 content of the paste are optimal in the diagonally shaded area surrounded by A-G in the figure based on the properties of the paste and the results of the discharge test. In this region, the amount of solution per 1 kg of lead powder is X (m17 kg), and the Pb SOa content in the absolutely dry state of the prepared slurry is y (%).
Then, 0.015≦y≦0,05x, y≦−〇,
04x+ 46.300≦x≦800.5≦y≦24.

Effects of the Invention As detailed above, according to the present invention, the discharge performance of a clad positive electrode plate can be significantly improved, and it has great industrial value.

[Brief explanation of drawings]

Figure 1 shows the amount of mixing solution to obtain a slurry paste and the Pb
FIG. 2 is a characteristic diagram showing the range of SO4 content, and the shaded range indicates a particularly preferable region in terms of production of a clad type positive electrode plate and discharge performance.

Claims (1)

[Claims] 1. A slurry paste prepared by kneading a mixture of lead powder and highly anisotropic graphite with dilute sulfuric acid, or by kneading the mixture with water and then adding dilute sulfuric acid, When the amount of kneading solution per 1 kg of powder is x (ml/kg) and the PbSO_4 content of the slurry in an absolutely dry state is y (%), 0.015x≦y≦0.05x, y≦-0.04
PbSO_4 in the range of x+46, 300≦x≦800, 5≦y≦24 and in an absolutely dry state
A positive electrode plate for a clad lead-acid battery characterized by being filled with a slurry-like paste having a certain content.